Date: Fri, 03 Jun 2005 17:58:40 -0700 From: Julian Elischer <julian@elischer.org> To: shiner chen <shiner_chen@yahoo.com.cn> Cc: freebsd-hackers@freebsd.org Subject: Re: a error about the kern_sendit Message-ID: <42A0FCC0.6010805@elischer.org> In-Reply-To: <20050603034129.34801.qmail@web15510.mail.cnb.yahoo.com> References: <20050603034129.34801.qmail@web15510.mail.cnb.yahoo.com>
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shiner chen wrote:
> i wrote a function to send the data of my a data structure in my kld by socket in kernel, the function as follow:
> the arg 1 is file descriptor of socket. the arg 2 is the address of data structure. the arg 3 is the length of data structure and it is 20 bytes .
>
> the error return by kern_sendit is EFAULT(14), i check the address of data structure ,but it is right!
> why ? who can tell me. thanks!!
>
> int loadinfo_send(int so_fd, struct thread *td,
> char *snd_buf, unsigned int uBufLen)
> {
> int st = 0;
>
> /* read */
> struct iovec aiov;
> struct msghdr msg;
>
> msg.msg_name = 0;
> msg.msg_namelen = 0;
> msg.msg_iov = &aiov;
> msg.msg_iovlen = 1;
> msg.msg_control = 0;
> msg.msg_flags = 0;
>
> /* do actual send operation now */
> aiov.iov_base = snd_buf ;
> aiov.iov_len = uBufLen;
> ///////// there is error////////////////////////
I think that aio is expected to be the
address of a userspace buffer.
kern_sendit() is expecting to get the address
info from the msg and passes it to
so->so_proto->pr_usrreqs->pru_sosend()
without there having ever been any work in making it
a kernel address.
an example of xxx->sosend() is sosend().
sosend uses uiomove() to bring the data in from user
space unless you have set the UIO_SYSSPACE
value for uio->uio_segflg.
Since the uio is added in kern_sendit()
you do not have the oportunity to change this.
possibly this is what keta_kern_sendit() does
but you do not show this function so I can not tell this.
I'm also dubious whether you can use an int
fd at that point.. are you runnin on behalf of
a specific process of which you know the fd for
the socket you want?
For in-kernel use of a socket yuo should look at either the
nfs code or the ng_ksocket code..
Not sure if this helps...
> /*st = kern_sendit(td, so_fd,&msg,0,0);*/
>
> st = keta_kern_sendit(td, control_so,&msg,0,0);
> if( st!=0 ){
> if ( st == EAGAIN ){
> loadinfo_msleep(1);
> }
> else{
> log(LOG_DEBUG,"in loadinfo_send, send error(%d)!\n",st);
> return st;
> }
> }
> log(LOG_DEBUG,"send successfully !\n");
> return st;
> }
>
>
>
> ---------------------------------
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